Low levels of minimal residual disease after induction chemotherapy for BCR-ABL1-negative acute lymphoblastic leukaemia in adults are clinically relevant

The aim of the present study was to evaluate the significance of low-level minimal/measurable residual disease (MRD) during early consolidation treatment in adult BCR-ABL1-negative acute lymphoblastic leukaemia. The MRD load was monitored by immunoglobulin/T-cell receptor rearrangements and assessed as negative [complete MRD response (CMR)], positive non-quantifiable (MRDnq) and positive quantifiable (MRDq). MRDnq before the first and second consolidation blocks had a comparable negative effect on survival as MRDq. The 5-year overall survival for CMR, MRDnq and MRDq at week 11 was 74 center dot 0%, 42 center dot 3% and 35 center dot 0% respectively. No central nervous system infiltration and MRD at week 11 were independent prognostic factors for survival on multivariate analysis (hazard ratios 0 center dot 32 and 2 center dot 25).